This invention relates to a self-venting valve for providing, and controlling the rate of, a smooth and continuous fluid flow.
It is known to provide molded plastic valves for dispensing liquid from containers, in particular disposable containers of the type popular for holding a liquid such as water, juice or detergent. One well known type of valve for this purpose is a so-called “rotary” valve. In this type of valve, a handle is rotatably actuated by a user to rotate a valve core within a valve housing that is attached to a container. Rotation of the core aligns an aperture in the core with an aperture in the housing to provide a passageway that allows liquid to flow from the container.
An alternative to the rotary valve is a so-called “push button” valve. This type has a resilient plastic valve diaphragm which, when pressed by a user, opens an aperture provided in the valve housing to allow liquid to flow from the container. The resilient plastic diaphragm, commonly referred to as a “push button”, can be arranged so that it positively seals the aperture when manual pressure is removed, thus providing for a self-closing valve. Tap valves of this type require the user to provide manual pressure to the push button throughout the liquid dispensing process, which can be inconvenient when dispensing large quantities of a liquid, particularly when one of the user's hands is needed to hold a receptacle, such as a drinking glass, leaving only one hand to actuate the push button.
Effective metering of the flow rate is generally more difficult to achieve with push button valves than it is with rotary valves. In practice, push button valves provide substantially only “ON/OFF” operation.
Also, there are known slide valves that require a user to push or pull a part of the valve in a certain direction to actuate the valve, but actuation of such a valve may cause the container to unintentionally slide in that direction. If, as is commonly the case, that direction is toward the user, the container could be pulled off the surface it is resting on, unless one hand is used to restrain the container. However, the user's second hand normally would be occupied holding the drinking glass or other receptacle.
Regardless of the valve type used, when a liquid is dispensed through an aperture in a container and valve, ambient pressure above the liquid level in the container drops and creates a partial vacuum. This vacuum must be filled by a volume of fluid—generally air—equal to the volume of liquid that has been removed to equalize the pressure within the container. In early containers, the pressure was equalized by external air drawn into the container through the same valve aperture through which the liquid exited the container. However, in such an arrangement, the external air attempting to enter the container would disrupt the outflow of liquid attempting to exit the container, thereby causing discontinuous liquid flow (i.e., “glugging”) and reducing the outflow rate.
It is known that continuous and smooth liquid flow can be achieved using containers that are capable of collapsing as liquid flows therefrom or using containers that are vented, because these types of containers are able to decrease the magnitude of the partial vacuum created above the liquid level inside the container without requiring air to flow into the container through the valve. However, a collapsible container, such as a balloon or bag, for example, may be easily damaged and may not be easily attached to a valve. A vented container may allow the contents to be spoiled by substantially continuous exposure to air and to be spilled from the vent. These problems can be addressed by providing a vent that is sealed until opened by the user (e.g., by puncturing), but once the vent is unsealed, spillage and spoilage become possible. A reclosable vent can be provided, but users are unlikely to bother reclosing the vent.
Accordingly, it would be advantageous to be able to provide a container with a valve that provides a smooth and continuous outflow of liquid therefrom by maintaining neutral atmospheric pressure within the container while dispensing the liquid, even when the container is unvented or substantially rigid, and that allows the liquid outflow rate to be varied.